Tuners do the selecting of desired signals from the total band of regard. For example, a television tuner may tune from channel 2 through channel 100, selecting a desired channel 8. In doing so, tuners must work in a variable signal environment, and thus are designed for satisfactory performance in the worse case environment.
It is well known in the art that the power consumption and dissipation for a tuner is very dependent on the tuner's linearity requirements, which are driven by characteristics of the incoming signal environment. It is also well known that a dense signal environment with large variation in individual signal strength requires a very linear receiver to avoid distorting the desired received signal. Conversely, environments with few signals with constant individual signal strengths require less linearity to avoid distortion.
Signals, depending on their use, have a maximum distortion level, above which there is definite performance degradation. Thus, tuners must be designed to produce no more than the maximum exceptable distortion when confronted with the worse case environment. When the severity of the environment is less than anticipated, the tuner is “over designed” requiring more power than if it was designed for the more benign-environment. Turners are designed with a simple power level and this power level is dependant upon turner design which, in turn, causes turner to be designed using maximum power levels.
Consequently, it is desirable to provide a tuner that requires only the power necessary to achieve exceptable distortion levels in a worse case and benign environments.